User manual

41
Instruction Manual
EL 3000 A Series
EN
Date: 09-09-2013
8. The analogue interface
Introduction
The analogue interface is a 15pole Sub-D socket and is
located at the rear side. It is designed to remotely control
the most important functions of the electronic load by
external hardware (eg. SPS, switches, relays) with it.
The load requires to be switched to external control
in order to use the analogue interface. This is done
by connecting Pin 7 (Remote) with ground (Pin 6) by
a jumper or switch. The status is then displayed like this:
Figure 15
Priorities
The analogue interface has priority over any other ope-
ration mode. Switching to external control can be done in
any situation (except when setup menu is active). Hereby
the set value inputs are activated and the set values for
the load can only be adjusted by means of an external
voltage source (PLC or 0...10V application) or with poten-
tiometers. See table „8.4 Pin assignment of the analogue
interface“) for an overview of the inputs.
Additionally, the control via the interface card is blocked
in this mode, but actual values can be read with it (i.e.
monitoring).
8.1 Important notes
For details also see „8.4 Pin assignment of the analogue
interface“.
Caution! The inputs are not protected against overvolta-
ges. Higher voltage than specied in section 8.4 on any
input of the analogue interface may damage the device!
Please read and follow these instructions carefully:
• Before connecting the hardware (with a Sub-D plug)
which is used to control the analogue interface, wire
all necessary connections and check the hardware
for not supplying >10V respectively not more than the
speciedvalue.
• The constant resistance regulation requires all four set
values (U, I, P, R) to be fed in, if it‘s not used three set
values(U,IundP)aresufcient.
• By default, constant resistance regulation is activated!
If not used, it should be deactivated by putting a bridge
from pin 12 (R-active) to pin 6 (DGND):
Pin 12 = Low = Resistance regulation inactive
Pin 12 = High = Resistance regulation active
• If resistance regulation is used, you can select the
resistance range before or while using the analogue
interface. Pin 13 (R-Range) is used to switch between
the two ranges:
Pin 13 = Low =Resistance range 2 is used
Pin 13 = High = Resistance range 1 is used (default)
Remote control
• The input Rem-SB (Remote Standby, Pin 8) overlays
the pushbutton Input on/off(4). That means, that you
can switch the load input off or on with this pin at any
time (even if the load was not set to external control
via the analogue interface) and as long as this pin is
tied to 0V (ground) the load input will be permanently
off and can not be set to on with the pushbutton Input
on/off(4) or via remote control by an interface card.
• The output VREF can be used to generate set values
for the set value inputs VSEL, CSEL, PSEL and RSEL.
For example: in case that only CC regulation is required,
the set value input VSEL has to be tied to 0V, PSEL
to VREF and CSEL can either be fed from an external
0...10V source or via a potentiometer (GND and VREF,
slider to CSEL). See also the table below.
• Adjustable rise/fall times and pulse widths like in the
Level A/B mode are not effective here. If a certain form
of amplitude-time-progression is favoured, it has to be
generated by an external function generator and fed in.
• The trigger input (Trigger In) has no function when
controlling the load via analogue interface (External
mode). That means that set value leaps have to be
generated with the signal that is fed in to the set value
inputs.
8.2 Example congurations
Thetablebelow showsexamplecongurationsforva-
rious single or combined regulation modes. It always
applies, that pin 7 (Remote) always has to be pulled
to 0V (DGnd) and pin 12 (R-Active) too, if resistance
regulation is not used.
Explanation:itisnotnecessarilyrequiredtogiveaxed
10V to any non-variable input. It can of course also be
a lower voltage in order to limit, for example, the power.
Best to tie the non-variable inputs to VREF respectively
to GND, if required.
Pin
VSEL CSEL PSEL RSEL R-active
Voltage regulation (CV) var. 10V 10V - L
Current regulation (CC) 0V var. 10V - L
Power regulation (CP) 0V 10V var. - L
Resistance regulation (CR) 0V 10V 10V var. H
Current & power (CC+CP) 0V var. var. - L
Current & resistance (CC+CR) 0V var. 10V var. H
„var.“ = variable set value of 0...10V, which can be, of course, pulsed
in order to emulate the Level A/B operation.
„H/L“ = High or Low, for level see table „Pin assignment of the analogue
interface“